Recently, various types of surveillance systems using cameras are widely used in industries, and the surveillance system using the cameras is actively utilized for security and monitoring.
Presently, most surveillance cameras for security, which capture images of a particular location and monitor a visitor or an intruder, are wide-range surveillance cameras that capture images of the entirety of a region to be monitored within a particular distance and a range of view angle.
Because the wide-range surveillance camera is a stationary camera that monitors a given large area, the wide-range surveillance camera has a limitation in terms of resolution. For this reason, a face of a person in a region to be monitored cannot be mostly recognized from the images captured by the wide-range surveillance camera.
Therefore, recently, a system having a camera, which dynamically tracks a person, is being developed.
Typically, to dynamically track and monitor people, vehicles, and objects at a long distance at the time of widely monitoring a large area, a panning function, a tilting function, and a zooming function are essentially required.
Here, the panning and tilting functions are carried out by a pan-tilt device, and the zooming function is carried out by a camera or a separate zoom lens mounted in the camera.
Various types of cameras for widely monitoring a large area are disclosed in Korean Patent Application Laid-Open Nos. 10-2010-0109125 and 10-2013-0002366 and the like.
In general, since an object to be monitored when monitoring a wide area is positioned at various positions from a short distance to a long distance and moves slowly or rapidly, a high-precision and high-speed change of an angle of the pan-tilt device are required to smoothly track the object.
For example, panning and tilting velocities for tracking an object, which is moving at a short distance from the camera, need to be high in terms of the speed and the precision, and high precision of panning and tilting angles is required to track an object that moves slowly at a long distance.
However, most of the presently developed pan-tilt devices cannot satisfy precision when a person moves 1 m at a running speed (10 m/s) at a long distance (100 m), and even though the pan-tilt device has an approximate function, the pan-tilt device is very expensive, and thus just used for military purpose or a special purpose.
A required function from another point of view is a function of adjusting a height, but the present surveillance camera is fixedly installed at a particular height, such that it is difficult to obtain data of a face of a person within a space to be monitored in a case in which the person wears a hat or the face is hidden by an umbrella or the like.